1. Field of the Invention
The present invention relates generally to a burner nozzle configured to resist failure and extend the useful lifetime of the nozzle.
2. Discussion of the Background
High temperature combustion is often employed in many industrial processes such as in fiberglass manufacturing. Burner nozzles suffer from common problems of corrosion and fouling in high temperature industrial processes. Water cooling of metallic nozzles is often used to prevent high temperature corrosion or melting. Although water cooling is effective in a relatively clean furnace atmosphere, it adds to the complexity of the combustion system and also could escalate the corrosion and fouling problem when the furnace atmosphere contains condensible vapors. Therefore, ceramic nozzles have been proposed for use with high temperature combustion as a way to avoid the need for water cooling. However, presently available ceramic nozzles tend to develop cracks due to thermal and other stresses, and are not considered dependable for many industrial applications.
FIG. 4 depicts a ceramic nozzle 100 manufactured by PRAXAIR for use with PRAXAIR industrial burners. The nozzle 100 includes a body 110 having a large cavity 112 that extends along a substantial portion thereof, and three outlet tubes 114, 116, and 118 extending off the cavity 112. The cavity 112 has an inlet 120 and the outlet tubes 114, 116, and 118, each have an outlet 122, 124, and 126, respectively. The cavity 112 creates a large void within the body 110. The body 110 includes an upper wall 128 with an indented portion 129 and a lower wall 130 with an indented portion 131. The inventors have observed that the nozzle 100 has a tendency to fail or crack at an end region of the cavity 112 where the cavity 112 joins with the tubes 114, 116, and 118, as indicated in FIG. 4 by crack 102. The relatively thin section of the walls 128 and 130 at the end region of the cavity 112 frequently prematurely fail, causing failure of the nozzle 100. The inventors of the present invention have observed that the burner nozzles depicted in FIG. 4 typically have a lifetime of three to five weeks of industrial use. As these burner nozzles are relatively expensive to replace, such premature failure of the burner nozzles can unnecessarily increase the operating costs of the burner.
Based upon the above observations by the inventors of the present invention, the inventors have determined that a burner nozzle is needed that will overcome the disadvantages discussed above.
An object of the present invention is to provide a burner nozzle with thick, strong exterior body walls that resist failure. The present invention advantageously provides a nozzle body having separate tubes extending therethrough. Since the tubes are generally separated in the present invention, the body does not have any significant cavities therein and the exterior walls of the body remain thick and strong, thereby resisting failure of the exterior walls.
The present invention advantageously provides a nozzle for a burner including a body having a first end adapted to attach to the burner and a second end configured to discharge gas and oxygen for combustion within an industrial furnace. The body is preferably configured as a flat flame burner nozzle such that it has a generally rectangular cross-sectional shape. The body preferably has a first tube, a second tube, and a third tube extending therethrough. Alternative embodiments can include two tubes, or four or more tubes, depending upon the desired output of the burner nozzle. The number and size of the tubes used are dependant upon the desired length and shape of the flame, and the volume of gas and oxygen flow through the nozzle. Each tube has an inlet on the first end of the body, and an outlet on the second end of the body. The tubes are configured to be separate along a substantial length of the body, thereby ensuring that the tubes are not joined together to form a large cavity within the body. Preferably, any overlap between the tubes does not extend beyond ten percent of the overall length of the body. The structure of the present invention provides thick, strong exterior walls of the body that resist failure.
In the first embodiment, the first tube, the second tube, and the third tube are all linear in order to simplify the manufacturing of the nozzle and provide a simplified flow of oxygen and gas through the body. Alternatively, the tubes can be configured to be non-linear, or can be configured to include several different section, such as a non-linear section and a linear section, plural linear sections in series, or plural non-linear sections in series. In the first embodiment the second tube is oriented to extend along a horizontal plane, while the first tube is angled upwards from the horizontal plane by an angle xcex81 and the linear third tube is angled downwards from the horizontal plane by an angle xcex11. Preferably, the angle xcex81 and the angle xcex11 are equivalent, although these angles can be configured to be different depending upon the shape and size of the flame desired. In the first embodiment, due to the linear configuration of the tubes, the angles of the tubes coincide with the angles of dispersion of the gas and oxygen from the nozzle. The angle of dispersion as used herein is defined as the angle of the discharge from each outlet in relation to the horizontal plane. Note that, an outlet will generally disperse fluid therefrom in a conical manner, rather than simply along the angle of dispersion.
The present invention further provides a second embodiment that includes a body having a first tube, a second tube, and a third tube. In the second embodiment, the tubes are configured to be separate along an entire length of the body, without any joining of the inlets or outlets. The first and third tubes each include a first linear section and a second linear section, while the second tube only include one linear section extending along the horizontal plane. The first linear sections extend parallel to the horizontal plane, while the second linear sections define the angles of dispersion for the first tube and the third tube. The use of first and second linear sections in the first and third tubes of the second embodiment provides for an increase in the dispersion angles for the first and third tubes in the second embodiment as compared to the dispersion angles for the first and third tubes in the first embodiment.